`start-vs-VisualFSharpSln.ps1`: build against a locally built hive Roslyn from its own packages by xperiandri · Pull Request #20528 · dotnet/fsharp

xperiandri · 2026-09-11T17:09:47Z

Description

Depends on #20467, which is the base of this branch. Only the last commit, "Build against a locally built hive Roslyn from its own packages", belongs to this pull request; please review it after #20467 merges.

#20467 teaches the script to read the Roslyn deployed in the target hive. When that Roslyn is a local build (a -dev version), it either matched the minor the repo flows and wrote no override, or stopped and asked for -RoslynVersion. Neither builds against the Roslyn F5 actually runs.

A Roslyn is built locally and deployed into a hive because its API surface differs from the flowed package: it is where an ExternalAccess contract lives before it flows. So a matching minor says nothing about whether the flowed packages will do, and asking for a published version gives up on the one that differs.

With this change:

A -dev version always overrides the flowed packages.
The override adds that Roslyn build's package folders to RestoreAdditionalProjectSources, because no feed carries its version. This has to go through the props import: Microsoft.FSharp.NetSdk.targets declares the property TreatAsLocalProperty and appends to it, so a command-line value would not survive.
-RoslynRepo names the Roslyn repository, defaulting to a roslyn folder next to this one. The script checks that it holds the package for that version and says so, instead of restore failing halfway with NU1101.

Shipped Roslyn versions behave as in #20467.

Checked with -DryRun:

Hive	Roslyn found	Result
`RoslynDev`	5.12.5-dev, deployed there	override with the Roslyn repo's `Shipping` and `NonShipping` package folders
`Foo`	none, so the installed 5.11.0-1.26424.5	override without extra sources
`RoslynDev` with `-RoslynRepo C:\no-such-roslyn`	5.12.5-dev	stops with "no repository at C:\no-such-roslyn; pass -RoslynRepo"

Tooling only; no compiler or IDE code path changes, so no release notes entry.

Checklist

Test cases added
Performance benchmarks added in case of performance changes
Release notes entry updated

🤖 Generated with Claude Code

github-actions · 2026-09-11T17:10:01Z

✅ No release notes required

T-Gro

🤖 🕵️ AI review — verify independently.

T-Gro · 2026-09-14T14:26:56Z

+    # RestoreAdditionalProjectSources has to arrive through the props import rather than on the command
+    # line: Microsoft.FSharp.NetSdk.targets declares it TreatAsLocalProperty and appends to it.
+    $sources =
+        if ($feeds) { "<RestoreAdditionalProjectSources>`$(RestoreAdditionalProjectSources);$($feeds -join ';')</RestoreAdditionalProjectSources>" }


🤖 🕵️ [P2] Repacked Roslyn packages ignored when the -dev version is unchanged: restore succeeds with the previous contents from NuGet's global-packages cache, despite the updated local feed.

.\start-vs-VisualFSharpSln.ps1 -RoslynVersion 5.10.0-dev -RoslynRepo 'C:\src\roslyn' # Change Roslyn APIs, rebuild and repack as the same 5.10.0-dev version. .\start-vs-VisualFSharpSln.ps1 -RoslynVersion 5.10.0-dev -RoslynRepo 'C:\src\roslyn' # Still consumes the first build's packages until their cache entries are removed.

Fixed in 1e2c85b: before restore, the script removes the global-packages entry ($env:NUGET_PACKAGES or ~\.nuget\packages) of every package the local feeds hold at that -dev version; -DryRun lists them instead.

T-Gro · 2026-09-14T14:26:56Z

+        throw "$RootSuffix runs a locally built Roslyn $version, which only its own packages provide, but there is no repository at $repo; pass -RoslynRepo."
+    }
+
+    $feeds = 'Shipping', 'NonShipping' | ForEach-Object { Join-Path $repo "artifacts\packages\Release\$_" }


🤖 🕵️ [P2] Valid relative repository passes validation but nested projects fail restore with NU1301: NuGet resolves the emitted relative sources against each project directory, not the launcher's working directory.

# From the F# checkout, with packed Roslyn packages in the sibling checkout: .\start-vs-VisualFSharpSln.ps1 -RoslynVersion 5.12.0-dev -RoslynRepo '..\roslyn'

Fixed in 1e2c85b: -RoslynRepo is resolved to an absolute path against the current location before the feeds are built.

T-Gro · 2026-09-14T14:26:56Z

+    # RestoreAdditionalProjectSources has to arrive through the props import rather than on the command
+    # line: Microsoft.FSharp.NetSdk.targets declares it TreatAsLocalProperty and appends to it.
+    $sources =
+        if ($feeds) { "<RestoreAdditionalProjectSources>`$(RestoreAdditionalProjectSources);$($feeds -join ';')</RestoreAdditionalProjectSources>" }


🤖 🕵️ [P2] & in an existing repository path makes the generated override invalid XML; restore stops with MSB4024 while parsing the unescaped feed path.

.\start-vs-VisualFSharpSln.ps1 -RoslynVersion 5.12.0-dev -RoslynRepo 'C:\src\roslyn&tree'

Fixed in 1e2c85b: the feed paths are XML-escaped (SecurityElement.Escape) when written into the props.

T-Gro · 2026-09-14T14:26:56Z

+# less about that than a message here does.
+function Get-RoslynDevFeeds([string]$repo, [string]$version) {
+    if (-not $repo) { $repo = Join-Path (Split-Path $PSScriptRoot) 'roslyn' }
+    if (-not (Test-Path $repo)) {


🤖 🕵️ [P2] Existing roslyn[1] repository rejected as nonexistent: both new Test-Path checks interpret brackets as wildcards instead of literal path characters.

.\start-vs-VisualFSharpSln.ps1 -RoslynVersion 5.12.0-dev -RoslynRepo 'C:\src\roslyn[1]'

Fixed in 1e2c85b: every Test-Path and Get-ChildItem in the script now uses -LiteralPath.

github-actions · 2026-09-27T23:39:22Z

🔍 Tooling Safety Check — Affects-Build-Infra, Affects-Design-Time, Affects-Restore
Affects-Build-Infra: Changes generated MSBuild configuration.
Affects-Design-Time: Changes Visual Studio launch behavior.
Affects-Restore: Changes package restore sources.

Generated by PR Tooling Safety Check · gpt56 1.7M · ◷

Copilot

Copilot review overview

🟡 Changes recommended

A missing package folder can break restore, and clearing the shared NuGet cache can disrupt other builds.

Review effort: Balanced
Findings: 1 · 1

Open (2)

Use an isolated NuGet cache for dev Roslyn builds · New
Avoid adding nonexistent Roslyn package sources · New

What changed in this PR

This PR lets the Visual Studio launch script build the F# extension against a locally built Roslyn deployed in the target hive, using that Roslyn build’s own packages.

Changes:

Override flowed Roslyn packages whenever the hive uses a -dev build.
Add the local Roslyn package folders as restore sources and clear cached copies before restoring.

File	Description
`start-vs-VisualFSharpSln.ps1`	Locates local Roslyn packages and configures the override, restore, and launch.

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xperiandri · 2026-09-29T17:21:19Z

        Write-Host "Would restore, then open $Solution in $DevEnv; F5 deploys into and launches $RootSuffix"
        return
    }
+    $stale | ForEach-Object { Remove-Item -LiteralPath $_ -Recurse -Force }


Keeping the shared cache. Only <id>/<version> entries at the -dev version are removed, and only for packages the local Roslyn feeds hold at that version. No published package carries that version, so nothing restored from a real feed is affected. The only other readers are builds against this same local Roslyn pack, and those would pick up the stale copy anyway.

A separate cache per launch would re-download every package the repo restores on each launch, and the launched VS would keep that cache for all its builds. Arcade deliberately keeps dev builds on the global cache to avoid that cost (InitializeNuGetPackageCachePath in eng/common/tools.ps1).

T-Gro

🤖 🕵️ Re-reviewed all recent changes as of c820c98; LGTM

A Roslyn built locally and deployed into the hive is there because its API surface differs from the flowed package: it is where an ExternalAccess contract lives before it flows. Matching the minor the repo flows therefore says nothing about whether the flowed packages will do, and refusing the dev version left no way to build against the Roslyn F5 actually runs. A dev version now always overrides, and the override adds the package folders of that Roslyn build to RestoreAdditionalProjectSources, since no feed carries its version. -RoslynRepo names the repository, next to this one by default, and the script checks that it actually holds the package before restore fails halfway with NU1101. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

…d drop stale -dev packages Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

T-Gro

🤖 🕵️ Re-reviewed all recent changes as of 4a165d7; LGTM

xperiandri requested a review from a team as a code owner September 11, 2026 17:09

github-project-automation Bot added this to F# Compiler and Tooling Sep 11, 2026

github-project-automation Bot moved this to New in F# Compiler and Tooling Sep 11, 2026

github-actions Bot added ⚠️ Affects-Build-Infra Tooling check: PR touches build infrastructure ⚠️ Affects-Restore Tooling check: PR touches NuGet packages or feeds labels Sep 11, 2026

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T-Gro reviewed Sep 14, 2026

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T-Gro added the AI-reviewed PR reviewed by AI review council label Sep 14, 2026

T-Gro self-requested a review September 14, 2026 14:28

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github-actions Bot added the ⚠️ Affects-Design-Time Tooling check: PR touches type providers or dependency manager label Sep 24, 2026

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Copilot AI balanced review requested due to automatic review settings September 29, 2026 16:56

Copilot started reviewing on behalf of xperiandri September 29, 2026 16:57 View session

Copilot AI reviewed Sep 29, 2026

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xperiandri force-pushed the start-vs-local-roslyn-packages branch from 84f3cdc to c820c98 Compare October 2, 2026 16:03

T-Gro reviewed Oct 3, 2026

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xperiandri and others added 3 commits October 8, 2026 02:58

Take -RoslynRepo literally and absolutely, escape it in the props, an…

71a24cb

…d drop stale -dev packages Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Add only the Roslyn package folders that exist as restore sources

4a165d7

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

xperiandri force-pushed the start-vs-local-roslyn-packages branch from c820c98 to 4a165d7 Compare October 8, 2026 01:11

T-Gro reviewed Oct 8, 2026

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xperiandri commented Sep 11, 2026

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✅ No release notes required

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github-actions Bot commented Sep 27, 2026

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